1. Field of the Invention
The present application relates to ankle braces. In particular, the present application relates to ankle braces that restrain the ankle and adjacent appendages.
2. Description of Related Art
The human ankle joint, medically known as the talocrural joint, is formed by three bones: the tibia, the fibula, and the talus. These bones are connected to themselves and to the other bones of the foot by ligaments. The ligaments, which are formed from tough bands of elastic tissue, help define and restrict the rotational movement of the foot relative to the leg. The ligaments of the ankle joint are grouped into two categories: (1) the lateral collateral ligaments, and (2) the medial collateral ligaments.
The lateral collateral ligaments include the anterior talofibular ligament (ATFL), calcaneofibular ligament, the talocalcaneal ligament, the posterior talocalcaneal ligament, and the posterior talofibular ligament (PTFL). The ATFL passes from the tip of the lateral malleolus to the talus anteriorly, and functions to limit plantar flexion of the joint. The calcaneofibular ligament passes from the lateral malleolus to the calcaneus, with the talocalcaneal ligament running at its base. The calcaneofibular ligament and the talocalcaneal ligament resist adduction. The PTFL passes from the tip of the lateral malleolus to the talus posteriorly. The posterior talocalcaneal extends this band to the calcaneus. The PTFL and the posterior talocalcaneal ligament both limit dorsiflexion.
The medial collateral ligaments, or deltoid ligament complex, include the tibionavicular ligament, the calcaneotibial ligament, the anterior talotibial ligament, and the posterior talotibial ligament. The tibionavicular ligament runs anteriorly form the medial malleolus to the navicular bone. The calcaneotibial ligament runs from the tip of the medial malleolus to the edge of the calcaneus. The tibionavicular ligament and the calcaneotibial ligament prevent abduction. The anterior and posterior talotibial ligaments run anteriorly and posteriorly between the medial malleolus and the talus. The anterior and posterior talotibial ligaments limit plantar flexion and dorsiflexion respectively.
The ATFL and the PTFL connect the bottoms of the tibia and fibula. The interosseous ligament spans the length of the tibia and fibula. The ATFL, the PTFL, and the interosseous ligament make up what is known as the syndesmotic ligament complex. The syndesmotic ligament cooperates with the ankle joints to allow the ankle to articulate.
A large portion of these ligaments is made up of collagenous fibers. During initial growth, collagenous fibers form in a web-like arrangement, due to the tension exerted by corresponding bones. The web-like arrangement supplies both elasticity and tensile strength to the ligaments. When a ligament is forced to stretch beyond its normal range, a sprain occurs. Ankle sprains are commonly categorized into three grades: Grade 1, characterized by slight stretching and some damage to the fibers (fibrils) of the ligament; Grade 2, characterized by partial tearing of the ligament, resulting in abnormal looseness (laxity) of the ankle joint; and Grade 3, characterized by complete tearing of the ligament, in which gross instability occurs.
Among these grades of ankle sprains, the two most common types are: (1) sprains to either the lateral ligaments or the medial ligaments of the ankle, which are referred to as “normal” ankle sprains; and (2) sprains to the syndesmotic ligament complex, which are known as “high” ankle sprains. Normal ankle sprains account for the vast majority of ankle sprains, occurring during the performance of ordinary activities. About 90% of normal ankle sprains are to the lateral ligaments, and about 10% of normal ankle sprains are to the medial ligaments. A person can sprain the lateral or medial ligaments of the ankle without affecting the syndesmotic ligaments. On the other hand, high ankle sprains are usually caused by injury or tearing of the syndesmotic ligaments. Most high ankle sprains are suffered by athletes undergoing extremely strenuous activity.
Sprained ankles can be healed; however, the healing process can take several weeks or months, depending upon the method of treatment and rehabilitation. Although most doctors recommend the well-known RICE treatment, i.e., rest, ice, compression, and elevation for the time period immediately after the ankle sprain, there are many methods of rehabilitating ankle sprains. For example, casts, wraps, and tape are often used to restrain and immobilize the ankle, so that the ligaments may heal through the reformation of the collagenous fibers. However, when the ankle is immobilized, there is a risk that the collagenous fibers will reform in a skewed arrangement due to a lack of tension on the ligaments. When ligaments reform with a skewed arrangement, they have decreased elasticity and tensile strength. As a result, subsequent conditioning must be undergone to resolve the skewed arrangement of the collagenous fibers and to regain the original elasticity and tensile strength of the ligament. Unfortunately, even after conditioning, ligaments that have been reformed with skewed growth of the collagenous fibers rarely obtain their original elasticity and tensile strength, because the collagenous fibers cannot fully rearrange themselves into the original web-like formation.
For high ankle sprains, while control of the exertion of the syndesmotic ligament is necessary, complete restraint of the ankle joint is not desirable. Because it is generally undesirable to completely immobilize the ankle during healing, ankle braces that allow for slight mobility of the ankle during the rehabilitation process are commonly prescribed.
Generally, ankle braces may be classified as one of three types: (1) ankle wraps; (2) ankle supports; and (3) functional ankle braces. Unfortunately, with current ankle braces, there is a trade-off between comfort and support. Ankle wraps are normally made of a neoprene material that surrounds the ankle. The problem with ankle wraps is that although they provide compression and warmth, i.e., comfort, they provide little or no stiffness, i.e., support.
Ankle supports usually consist of two stirrups and reinforcing elements that are secured along the sides of the ankle. These ankle supports compress the fibula and tibia toward each other in an attempt to allow the syndesmotic ligaments to heal. However, because the fibula extends slightly below the tibia, when the ankle rolls, shear is transferred to the fibula, thereby rendering the ankle support inadequate. Some ankle supports are multi-piece devices held together with straps or laces. These lace-up devices are difficult to administer and do not provide adequate stiffness.
Functional ankle braces typically consists of soft members that are connected to rigid frames. The rigid frames are multi-piece assemblies that are held together with flexible adjustment straps. These functional ankle braces compress the bones of the ankle toward one another, and constrain movement of the ankle relative to the leg. Unfortunately, although the soft members can adapt somewhat to the contours of the ankle, the stiff frames do not fit well, primarily because the frame members are rigid and the connecting straps are flexible. When the stiff frames are tightened around a movable joint, such as the ankle, the user experiences discomfort. Other problems are that the stiff frames, which are often made of aluminum, cannot be formed in the field, and are too hard to get fitted properly. More importantly, these types of ankle braces are not shaped, configured, or designed to properly account for the anatomy and degree of bending between the ankle and leg. In addition, the adjustment straps on conventional functional ankle braces pose many problems, for example, they require two hands to fasten them about the rigid frames, the tension changes each time they are fasten and unfastened, and they are located at places that cause discomfort, for example, around the Achilles tendon. This makes them difficult to administer, particularly when the braces are applied and taken off repeatedly.
Although great strides have been made in the area of treating ankle sprains, many shortcomings remain.